Although there were many inspired writings as early as 40 AD there was no New Testament for another 300 years.
The NT Scriptures were used and considered authoritative from the time they were written because they were penned by the Apostles or those close to them.
They were compiled later to delineate them from competing pseudo scripture; that doesn't mean they were not considered authoritative from the beginning.
>> “Although there were many inspired writings as early as 40 AD there was no New Testament for another 300 years.” <<
.
An ugly falsehood.
All of the NT writings except the late writings of John were complete within 35 years +/- 0f the day Christ ascended.
The 300 years is when the pagan catholic church was formed by the Pharisees in Rome.